A head-mounted display (HMD) has been known as a key device that provides the user with a vivid and powerful visual experience. For example, a technique that employs the HMD for an attraction in an amusement park, a video game, or the like has been known (see JP-A-5-305181, JP-A-2000-210468, and JP-A-2003-125313, for example).
When playing a game using the HMD as a display device, the player wears the HMD with both hands before starting the game. Specifically, the player wears the HMD without holding the game controller. The player holds the game controller after wearing the HMD. However, it may be difficult for the player to visually determine the position of the game controller in a state in which the player wears the HMD. When the HMD is a non-see-through HMD, the player must grope for the game controller since the player cannot observe the state of the external world.
The player may easily lose the sense of distance and the sense of direction (i.e., become unable to determine the position of the game controller) while the player is checking the state of the HMD worn on the head by moving (tilting) the head, for example. In particular, young people show such a tendency. This type of inconvenience also occurs when the player has temporarily put aside the game controller during the game, for example.